Recommended reading before making your choice:
Dual and Multi WAN Router Review - Are there some REALLY good ones out there?
http://gpsinformation.info/joe/routers/MultiWANroouters.htmlD-Link DI-LB604 is not recommended, and actually it is now discontinued.
For SOHO applications, Linksys products are always recommended. Linksys/Cisco RV042 is a good candidate, It also provides VPN support which is essential for SOHO users.
Cisco RV042 4-port 10/100 VPN Router - Dual WAN
https://www.cisco.com/en/US/products/ps9925/index.htmlLinksys RV042 Review: Solid Dual WAN, VPN Performer
http://www.smallnetbuilder.com/lanwan/lanwan-reviews/30186-linksys-rv042-review-solid-dual-wan-vpn-performer